House Minority Leader Nancy Pelosi on Thursday flatly rejected talk of delaying a mandate in President Obama’s health care law that requires most Americans to acquire some form of health insurance or pay a fine.

Ms. Pelosi, California Democrat, was asked if there was “any virtue” in a Republican proposal to put off the individual mandate, since the White House has decided to delay, to 2015, a clause requiring firms with 50 or more workers to offer health insurance or face penalties.

Republicans have questioned whether Mr. Obama has the authority to delay the mandate, since it is written into the law. In a pair of blog posts, the administration said it was technically putting off the enforcement of reporting requirements and penalties associated with the mandate.

“Certain reporting by businesses, that could be perceived as onerous, that reporting requirement was delayed, and partially to review how it would work and how it could be better,” she said. “It was not a delay of the mandate for the businesses, and there shouldn’t be a delay of the mandate for individuals.”